The precipitate being washed with cold water and digested in alcohol, this dissolves the emetia, and by evaporating the solution the salt is procured. The residue is re-dissolved in a dilute acid, and the emetia precipitated by a salifiable base. Emetia 2, when pure, is white, inodorous, slightly bitter, easily powdered, and persistent in the air : but it is usually of a reddish brown colour, and in transparent scales. When exposed to a heat stronger than that of boiling water, it is decomposed; furnishing water, carbonic acid, some oil, and acetic acid, charcoal being left. It is sparingly soluble in cold water, and when pure does not deliquesce in a moist atmosphere, although it deliquesces when in the coloured state. It is soluble in alcohol, but not in ether. It is precipitated from its solutions by gallic acid and acetate of lead. To detail the action of other chymical agents on this body is here unnecessary; the results are sufficient to characterise it as a substance sui generis. According to Pelletier pure emetia consists of 64.57 of carbon, 22.95 of oxygen, 7.77 of hydrogen, and 4 of nitrogen.

Besides emetia, ipecacuanha has been found, by the experiments of the above chymists, to contain a fatty matter, wax, resin, gum, starch, extractive, albumen, gallic acid, and lignine.

1 The title of Ipecacuan is generally given to the roots of the following plants, besides those mentioned above, in South America: Viola parviflora, V. Ipecacuanha, V. Calceolaria, Cynanchum Ipecacuanha, C. tomentosum, and Asclepias curassavica; and according to M. Martius, to Richardsonia scabra, R. emetica, Polygala, Poaya, Ionidium Ipecacuanha, I. brevicaule, I. urtiaefolium, Chio-cocca anguifuga, C. densifolia, Manettia cordifolia; and sometimes to Euphorbia Ipecacuanha, Dorstenia Brasiliensis, and D. arifolia.

In St. Domingo, several species of Ruellia, which provoke vomiting, are named false Ipecacuan.-Nouveau Dictionnaire d'Histoire Naturette, art. Ipecacuanha.

The medicinal value of ipecacuanha depends, undoubtedly, on the quantity of emetia it contains; and this varies in the three varieties of the root found in the shops. MM. Majendie and Pelletier obtained 16 parts of it in 100 of the cortical part of ipecacuanha, the root of Cephaelis Ipecacuanhal; 14 in 100 of the red annulated variety; 9 in 100 of the striated ipecacuanha, the root of the Pyschotria emetica 2; and 5 only in 100 of a white ipecacuanha, the root of the Viola emetica3 The woody pith even of the brown variety contains very little emetia, and hence it should be separated in reducing the root to the form of powder.

1 Vide Ann.de Chyrn. et de Phys. iv. p. 172., and Lond. Med. Repository, viii. p. 252.; also Dictionnaire de Drogues, t. iii. p. 261. 2 The name is derived from Vomo.

Experiments made with emetia on animals, prove that it is emetic and purgative, in doses of half a grain, and exerts a specific action on the lungs and mucous membrane of the intestinal canal, and has also narcotic properties: it may be employed instead of ipecacuanha in every case in which this medicine is useful, the dose being more easily regulated, and the effects more certain: but the nausea which it causes continues longer than that of Ipecacuanha. When taken in an over-dose, its action can be instantly paralysed by decoction of galls.

The powder of ipecacuanha is apt to become inert by keeping : and therefore it should be preserved in small phials, well corked, and not exposed to the light. Long-continued boiling also renders it inert Medical properties and uses.-Ipecacuanha, when administered in large doses, is emetic; in smaller ones, diaphoretic and expectorant; and in still smaller doses, it acts as a stomachic, stimulating and giving energy to the digestive organs. As an emetic, it is mild, safe, and certain in its operation; but it is a mistake that, when given in larger doses than are necessary, it does not operate more violently, but only in a shorter space of time. It does not act so quickly as many other emetic substances; but it evacuates completely the contents of the stomach, and does not so much weaken it as antimonial emetics. It is given at the commencement of continual fevers, the progress of which is sometimes cut short by its operation; and it is also frequently found to stop the paroxysm of an intermittent, when given immediately before the accession of the cold stage.

At the commencement of inflammation of the pharynx, larynx, and trachea, when the inflammation does not run very high, in cynanche tonsillaris, purulent ophthalmy, abscess, and every case in which it is necessary to evacuate the stomach, or to increase the energy of the absorbent system by full vomiting, ipecacuan has been found useful. As an emetic, however, it is contra-indicated when there is any reason for suspecting inflammation of the encephalon, passive haemorrhagy, or hernia; and in the advanced stage of typhus fevers, when the pulse is feeble, and the strength much diminished; but in these instances all emetics are hurtful. In doses sufficient to excite nausea without producing vomiting, ipecacuan is given with excellent effects in dysentery1 , and obstinate diarrhoea, in which cases its efficacy seems to arise in a great degree from the nausea, which is kept up by the repetition of the small doses, diminishing the arterial excitement, and determining to the surface; and partly so, as Cullen supposed, from its producing a steady determination of the peristaltic motion of the intestines downwards.2 Perhaps, also, to these first-mentioned effects of the nausea may be attributed much of the benefit which results from the use of ipecacuan in spasmodic asthma, dyspnoea, pertussis, and epilepsy.

In the first of these diseases its emetic power is taken advantage of to relieve the paroxysm, after which it is given in repeated small doses to prevent its return.3 In nauseating doses also, owing to the nausea lessening the force of the circulation, it has been employed with the best success in uterine and pulmonary haemorrhages. As a sudorific, it is used in acute rheumatism, arthritic affections, dropsy, and other diseases in which sweating is necessary. It is generally given in these cases, in combination with opium and neutral salts, according to the mode introduced by Dover. (See Pulvis Ipecacuanhae compositus.) But we have found it in combination with opium alone in a larger proportion, more efficacious, particularly in rheumatism. Its expectorant powers have been found exceedingly useful in catarrhal affections, pneumonia after bleeding, and in the early stage of phthisis, in which its diaphoretic effect is not injurious as in the latter stage of that disease.

1 The components procured from 100 parts of brown ipecacuanha were as follows: of fatty and oily matter 2; emetic matter (emetia) 16; wax 6; gum 10; starch 42; and ligneous matter 20; the remaining four parts being regarded as loss.

2 100 parts of the red variety yielded, of fatty matter 2; emetia 14; gum 16; starch 18; woody matter 48; with merely a trace of wax, and two of loss.

3 From 100 parts of the white ipecacuanha were obtained, of emetia 5; gum 35; vegeto-animal matter 1; and woody matter 57; besides three of loss.

The emetic operation of ipecacuanha is quickened by combining it with tartar emetic; and, on the contrary, it is moderated by opium, and extract of gentian; and destroyed by vegetable infusions containing tannin, and by vegetable acids. Opium, however, is rendered less narcotic when combined with ipecacuanha, although its power of allaying pain is not diminished, while the sudorific effect of the ipecacuanha is much augmented by the combination. We do not, however, agree in opinion with those who think that it is to be relied on as an antidote against the deleterious effects of opium; its emetic effect being too slow, and checked by the opium. The infusion of nutgalls is the only certain and powerful antidote for an overdose of ipecacuanha, instantly rendering it inert.

1 Piso, Helvetius, Cleghorn, Pringle.

2 Materia Med. ii. 477.

3 Akenside.

Idiosyncracy occasions some persons to be affected with the most distressing sensation of suffocation, and others suffer from violent sneezing, by the effluvia of this root.

Ipecacuanha is exhibited in substance, and in aqueous and vinous infusions; and on the Continent a syrup of it is used for children.1 The dose of the powder, to produce full vomiting, is from grs. xx. to 3 ss.; and of the aqueous infusion, which is made by macerating for an hour 3 ij. of the powdered root in f vj. of boiling water, and filtering, f j. or f jss. may be given every half hour till vomiting is excited. The emetic effect is continued, and rendered easier to the patient, by drinking, in the intervals of vomiting, large draughts of tepid water. For producing the other effects of ipecacuanha, it is given in doses of one, two, or three grains, generally in the form of pills, repeated every four or five hours: but although its sudorific effect, when begun, is aided and kept up by the use of warm fluids, yet these must not be drunk soon after the dose has been taken.

Officinal preparations.-Pulvis Ipecacuanha compositus, L. D. Vinum Ipecacuanhae, L. ED.